Continuous variable Aperture Cold Stop

Under the Phase-I program, OKSI has demonstrated a simple solution for a continuously variable aperture cold stop for IR cameras. The variable cold stop was shown to work very smoothly and reliably at liquid nitrogen temperatures in vacuum, in a standardpour-fill dewar.Under Phase-II, OKSI will add into the dewar a focal plane array and camera electronics, and will develop a cold stop control software as an automatic brightness control for image capture with the camera.In parallel, OKSI will also adapt the design to closed cycle hermetically sealed dewars in use with Stirling engines for tactical applications. A SADA type dewar will be used for the development of a fully functional prototype demonstrating the conceptsof both a dual aperture and a variable aperture cold stop in such tactical dewars.The advantage of using a variable aperture cold stop to the DoD is that the same IR optical system can be used for both wide field search and automated target recognition, and long range target identification without compromising optimal image quality ofeither task. Thus, this system reduces the number of types of cameras which need to be inventoried. In addition, automatic brightness control can be used for high dynamic range scene imaging, greatly reducing camera saturation. Saturation may be aproblem when viewing a battle field when firing weapons, etc.Two devices are developed under this program, one is for a pour-fill dewar camera and the other for Stirling engine cooled cameras. The former has applications in laboratory and researchenvironments, while the latter has applications in tactical systems. On the commercial side, OKSI is already working with a commercial partner, a domestic IR camera manufacturer, that has expressed interest in testing the technology. In addition, the DoDwill most likely become a significant user for the technology. For these tactical applications, OKSI will license the technology to vendors producing IR equipment for the DoD.The technology of CVA/CS for IR cameras, for use in various science, technology & intelligence missions such as target signature acquisition, also supports the mission of a number of DoD branches and agencies including Army SMDC, MSIC, MDA, ISTEF, AFRL,etc.